Yep I had the same thought so I created a file edit.php under root/test/user/edit.php
I can view it (but that is true for the moodle one as well) and it runs this...
<html>
<head>
<title>PHP Test</title>
</head>
<body>
<?php echo '<p>Hello World</p>';
$content = "some text here";
$fp = fopen($_SERVER['DOCUMENT_ROOT'] . "/myText.txt","wb");
fwrite($fp,$content);
fclose($fp);
?>
</body>
</html>
This is stand alone moodle (no wordpress)